Power line EMF exposure
Last reviewed: 19 October 2026
Overhead power lines are the most visible source of extremely low-frequency (ELF) electric and magnetic fields — the 50/60 Hz fields that also come from household wiring and every appliance that plugs into it. Unlike phone or router signals, these fields do not carry enough energy to break chemical bonds; the question the dated research addresses is what field strengths people actually experience, and against which limits they are assessed.
Typical levels and limits, with dated sources
- Magnetic-field background in most homes away from lines is roughly 0.01–0.3 µT, varying with wiring, appliances and housing type (WHO, Environmental Health Criteria 238, 2007).
- Directly beneath large transmission lines the magnetic field can reach a few tens of microtesla, falling off rapidly with distance from the line (WHO, Environmental Health Criteria 238, 2007).
- The ICNIRP public reference level for power-frequency magnetic fields is 200 µT at 50/60 Hz — two to four orders of magnitude above typical home backgrounds (ICNIRP, 2010, Health Physics 99(6): 818–836).
- IARC classified ELF magnetic fields as "possibly carcinogenic" (Group 2B) in 2002, on limited evidence from epidemiological studies that associated long-term average exposure above roughly 0.3–0.4 µT with a doubling of childhood leukaemia risk; no causal mechanism is established and chance or bias could not be ruled out (IARC Monographs Vol. 80, 2002; WHO, Environmental Health Criteria 238, 2007).
- WHO's position is that the established short-term effects are prevented by the guidelines, and that evidence for long-term effects is limited and research continues (WHO, Environmental Health Criteria 238, 2007).
How distance changes exposure
- The magnetic field near a line falls off steeply with distance: our calculator applies an inverse-cube law within 20 metres of a line and inverse-square beyond it, so doubling your distance cuts the modelled field to roughly an eighth within that 20-metre window.
- In practice this is why the same 400 kV line that produces fields of tens of microtesla directly beneath it produces fields comparable with the home background at typical garden distances (WHO, Environmental Health Criteria 238, 2007).
- Magnetic fields pass through most building materials, so walls reduce line fields much less than they reduce radio signals.
Try it in the calculator
This link opens the calculator with the High Voltage Power Line (400kV) emitter pre-selected — set the distance to your nearest line and the hours you spend there. A Transformer Station emitter is also available for substations.
Open the calculator — High Voltage Power Line
Sources
- ICNIRP (2010), "Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz)", Health Physics 99(6): 818–836.
- WHO (2007), "Extremely low frequency fields", Environmental Health Criteria 238, World Health Organization, 2007.
- IARC (2002), "Non-ionizing radiation, Part 1: static and extremely low-frequency (ELF) electric and magnetic fields", IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 80.
Educational information, not medical advice. Numbers above are as stated by their dated sources; our calculator's output is a model-based estimate, not a measurement, and it is not a substitute for an on-site survey with a calibrated meter. No adverse health effects are confirmed below international limits, and research on long-term effects is ongoing — see About for our editorial position.